1. Field of the Invention
This invention relates to clothes washing machines in general, and front-loading clothes washing machines which are equipped with a particular, improved type of door interlock arrangement as a safety provision, in particular.
2. Description of the Related Art
Household-type clothes washing machines are known to be equipped with different types of variously featured door interlock arrangements. Such door interlock systems can be grouped into one of the following categories according to their operating principle:
1) Devices keeping the door locked throughout the washing process and allowing delayed (i.e. after 1 to 2 minutes) door release with respect to the actual moment at which the machine is de-energized upon completing its duty cycle.
This type of safety door interlock arrangement is effective in protecting the user against his/her being able to gain access to dangerous moving parts, i.e. parts rotating at dangerous speeds, such as during the spin-extraction phase of the process. It also prevents the user from unduly opening the loading door of the machine even in the remaining portions of the washing cycle in the case of a faulty condition arising in washing machines equipped with an electronically controlled driving motor.
However, this type of safety door interlock arrangement has two major drawbacks: the first one is related to the fact that it forces the user to wait a couple of minutes each time that he/she wants for any reason to open the loading door of the machine during the washing cycle, even during phases thereof that do not involve dangerous rotating speeds of the drum.
The second drawback is apparent when the main on-off switch of the washing machine is switched on and the loading door of that same machine is open. Under such conditions, the washing machine would readily start operating as soon as its door is closed, thereby activating the process phase that is set on the program selector switch and causing the loading door to be locked under the action of the door interlock device itself.
Such a door closure under the above-mentioned conditions may obviously occur in a fully unintentional way and, as a consequence, may give rise to accidents with serious damage not only to things, but also to children and animals that may have accidentally climbed into the drum of the washing machine when the loading door was open and the drum was standing still.
2) Devices keeping the door locked only when the drum rotates at dangerous speeds, i.e. during spin-extraction phases, with a provision allowing for delayed door release after de-energization of the machine.
Such safety door interlock arrangements are only effective in protecting the user against accidents caused by improper door openings during spin-extraction phases (since no dangerous rotating speed is involved in the other phases of the cycle) and have the advantage of allowing the loading door to be readily opened in all other phases of the washing process. However, they have a major drawback in that they still practically enable accidents of the type described as the second major drawback under 1) above to occur.
3) Devices keeping the door locked through the action of an electromagnet.
These door interlock devices enable the loading door of the washing machine to be opened during any phase of the washing process in which the drum is not rotating at any dangerous speed.
When on the contrary the drum is rotating at a dangerous speed, there are further devices provided inside the machine to prevent the door interlock arrangement from becoming de-energized due to normal handling by the user and, as a consequence, the loading door from being opened.
However, such a type of door interlock arrangement has a third major drawback in that, if the solenoid, or coil, of the interlock device happens to be de-energized due to any faulty condition or by accident, the washing machine remains electrically energized and, therefore, enabled to keep performing all phases provided for by the washing process being carried on (including those involving dangerous operating conditions), while the door can be opened at any moment.